In mobile communication, high-speed data transmission has been demanded heretofore. In a 3GPP (3rd Generation Partnership Project), LTE (Long Term Evolution) has been increasingly standardized as a standard that enables high-speed transmission and its specifications are being completed. In an uplink in LTE, DFT-S-OFDM (“Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing”, which is also referred to as “SC-FDMA”) is adopted. Because DFT-S-OFDM can multiplex a frequency spectrum of each user in a frequency domain without using a guard band, the spectral efficiency is considered to be high.
More recently, LTE-Advanced (LTE-A) as an enhancement of LTE has been standardized as a 4th generation mobile communication system. LTE-A needs to support a higher spectral efficiency and a wider frequency band than that of LTE while maintaining backward compatibility with LTE. Hence, in order to achieve the higher spectral efficiency, with respect to DFT-S-OFDM, Clustered DFT-S-OFDM that divides a spectrum into a plurality of clusters and allocates the spectrums to frequency in unit of cluster is proposed.
Further, although in LTE, each terminal cannot perform simultaneous transmission from two antennas due to factors such as terminal costs, in LTE-A as an enhancement of LTE, transmission using a plurality of transmission antennas is discussed to achieve high-speed large-capacity communication. Particularly, SU-MIMO (Single User Multiple Input Multiple Output) that can improve a user throughput is one of the most promising technologies to be adopted.
FIG. 20 is a diagram showing configuration of a transmitter described in a non-patent literature 1. The non-patent literature 1 discloses an example of MIMO in previously-existing single carrier transmission. In FIG. 20, transmission data is divided for each antenna by a S/P conversion part 310. Here, it is assumed that the number of antennas is N. After that, modulation parts 311-1 to 311-Nt modulate the data into modulation symbols by QPSK (Quaternary Phase Shift Keying) or 16 QAM (Quadrature Amplitude Modulation) or the like. At this time, data is multiplexed with a pilot block (which is also referred to as pilot symbol or reference signal) through a copy part 313 and a circulation delay part 314. After that, GI is inserted by +GI (Guard Interval, CP: Cyclic Prefix having the same meaning as GI is also used) parts 312-1 to 312-Nt and signals are transmitted from antennas 315-1 to 315-Nt.
FIG. 21 is a diagram showing configuration of a receiver disclosed in the non-patent literature 1. Signals transmitted from the transmitter are received by antennas 410-1 to 410-Nr of the receiver. In the receiver, —GI parts 411-1 to 411-Nr provided at the antennas 410-1 to 410-Nr remove guard interval and FFT parts 412-1 to 412-Nr perform FFT (Fast Fourier Transform) for each antenna. When the frequency domain signal after FFT is the pilot symbol, a channel estimation part 413 performs channel estimation, and when the frequency domain signal after FFT is the data signal, a separation part 414 performs MIMO separation processing. Separated signals are returned to time domain signals by IFFT (Inverse FFT) parts 415-1 to 415-Nt and then, demodulated by demodulation parts 416-1 to 416-Nt based on the modulation in the transmitter, and finally, the signal for each antenna is P/S converted by a P/S conversion part 417 to extract data. With the above-mentioned configuration, in single carrier transmission, MIMO multiplexing can be realized.    [Non-patent literature 1] T. Fujimori, K. Takeda, K. Ozaki, A. Nakajima, and F. Adachi, “Channel Estimation Using Cyclic Delay Pilot for MIMO Transmission,” Proc. The 4th IEEE VTS Asia Pacific Wireless Communications Symposium, National Chiao Tung University, Hsinchu, Taiwan, 20-21, Aug. 2007.